The present invention relates to the field of semiconductor devices and integrated circuits, and more specifically to techniques and devices for a read-only memory cell.
The age of information and electronic commerce has been made possible by the development of semiconductor technology and integrated circuits. Integrated circuits are sometimes referred to as “chips.” Integrated circuits have been widely adopted and are used in many products in the areas of computers and other programmed machines, consumer electronics, telecommunications and networking equipment, wired and wireless telephony, electronic storage and recording devices, industrial automation, and medical instruments, just to name a few. Integrated circuits are the foundation of the internet and other on-line technologies including the World Wide Web (WWW).
There is a continuing demand for electronic products that are easier to use, more accessible to greater numbers of users, provide more features, and generally address the needs of consumers and customers. Integrated circuit technology continues to advance rapidly. With new advances in technology, more of these needs are addressed. Furthermore, new advances may also bring about fundamental changes in technology that profoundly impact and greatly enhance the products of the future.
The building blocks of an integrated circuit are electrical and electronic elements. These elements include transistors, diodes, resistors, and capacitors. There may be many numbers of these elements on a single integrated circuit. Improvements in the electrical elements and the development of new types of electrical elements will enhance the performance, functionality, and size of the integrated circuit. As an example, a basic electrical property used in an integrated circuit is resistance (also known as “impedance”). In fact, the operation of every integrated circuit is affected to some extent by on-chip electrical resistance. Resistors and other resistive elements are used in the implementation of many circuits on an integrated circuit.
An application of a semiconductor device having a variable impedance may be used to implement a memory cell. A memory cell is the building block of memory integrated circuits and storage systems such as read-only memories, random access memories, content addressable memories, and many others. Memories are a building block for computers and other programmed machines.
As can be appreciated, there is a need to provide techniques and devices for implementing variable impedances and memory cells for integrated circuits.